Calling device



Feb. 5, 1946. J.E. BoH I 2,394,360 I CALLING DEVICE Filed Nov. 28, 1941 2 Sheets-Sheet 1 hum-5&5]:

JUL/527702":

Feb. 5, 1946. J 0514 2,394,360

CALLING DEVICE" File d Nov. 28, 1941 2 Sheets-Sheet 2 "III- .mnml E 69 J5me E505]? Patented Feb. 5, 1946 UNITED STATES v PAT EN T F E [C E CALLING DEVICE JamesE; Bosh,,Berwyn,.Ill., assignor toKellogg' Switchboard and Supply Company, Chicago, 111., a corporation of Illinois Application November 28, 194.1, .Serial..No.. 420,871.

Thi invention. relates to calling; devices: of the dial type commonly. used in: automatic telephone systems to transmit, trains of; impulses corresponding respectively: to the digits. inidesiredtelephone-numbers; and for similar, purposes in signaling system generally;

One object of the invention is toproduce anew and. improved dial-type. calling device: capable of withstanding prolonged hard. usage, withou losing its adjustment.

Ayfurther object is-to-produce a calling devio which is" quiet in. operation and. in: which the parts are sturdily'constructed to-insureliong life.

A general feature of the improved calling device is that the'relatively' delicate contact'springs and the governor: parts. are-fully encloseditopro tect them against inadvertent bending; jamming, or fouling incidental to the. transportation and installation of the calling device, and; incidental to the repair or maintenance of? the telephone substation set;- or other equipment in association with which. the calling device maybe installed.

A specific feature: is; that the caselor; housing of. the calling deviceis-zin the formaof aninverted cup closed by a rear: plate; upon the inside surface ofv which are mounted the principal moving parts of the calling devicaaswella's the various assemblies of contact springs; all; of which are thus within the case and are thereby protected against unintentional interference.

A further specific feature isthat: the otherwise exposed'parts ofthe-governor, mountedon" the rear. of the above-mentioned. back plate, areprortected from accidental. interference: and from foreign particles by being pI'OVidEdlWithi anindividual enclosure or housing.

Another feature that each of. the pawls is provided with a. non-metallic stop which avoids noisy metallic clicks otherwise occurring during operation of the. calling device.

Other objects and features of the inventionwill appear as the description progresses.

Referring now to the'ac'c'ompanying drawings, comprising Figs. 1 to 13, they show sufiicient views of a calling device constructed in accordance with the features of the invention to enable the invention to be understood:

Fig. 1' is a rear view of the improved calling device, with the-protecting cover'removed from the governor;

Fig. 2 is a; front view of the calling device;

Fig. 3 is a front viewwith the dial and the housing cup removed, showing the parts lying in front of the backplate I '0 Fig. 4 is a. further front view with the drive plate 2!. and attached parts removed to afford a view of. the parts lying underneath:

Fig. 5 is a still further front viewwithaddition- 9.1 parts removed;

Fig. 6 is a View of the device as seen edgewise from: below, withv the dial. and housing cup removed, along with certainother parts;

Fig, 7 is-a view partly in section,.as seen from the left inF-ig. 2;

ig. 8-is aview as seen from the left in Fig. 2', withthe dial and housing cupremovedand with certainparts. broken away;

Fig, 9 is a sectional view asseen fromtheleft in. Fig. 2, showing theprincipal structuralparts;

Figs.v 10, 11,, and 12 are enlarged views of portions, of the. improved. governor mechanism; and

Fig. 131s. a leftside view. of the improved. calling device installed in a telephone desk stand'95, fragmentarily shown in section.

As shown in Fig. 2, the control portion of, the calling devicelis the dial. |,.which is provided with ten finger holes 2 beneathwhich lies the numeral ring 3, having the. illustrated numerals I to 9 and 0 thereon. The dial I may be rotated in a clockwise direction by placing a finger. in the desired one of the finger. hol'es.2' and pulling the dial around until the finger encountersthe finger stop 4. When released, the dial l proceeds under stored spring power to the normal position illustrated,. generating on its return movement a number of impulses depending upon which finger hole-was used for the operation.

As seen inFigs. 7 and 9, the dial I ismounted on the front or hub portion I9 of the main shaft l8, and held there by the retaining screw 5. Screw 5 also retains card holder 6', along with transparent card protector 1 and instruction card 8.

The back plate Ill; shown in profile in Fig. 1', is fitted flush into the rearmost portion of the cup-like housing 9, a shown best in Figs. 'Tand' 9. The back plate is provided with three attachment'lugs ll, 12, and I3, indicated in dotted outline in Fig. I and shown in Figs. 3 to 5'. Each of these" lugs-may be attached to the casing 9 by a countersunk screw, as indicated in Figs. 7' and 9.

As shown best in Figs. 5 and 9', a centrally 10- called main bearing I7 is firmly mounted in mainbearing bracket l 4. 'Ihe'main-bearing bracket M hearing. The enlarged main-shaft portion followingthe shoulder assists in aligning the-drive assembly comprising parts 22 and 23.

V The drive plate 2| (Figs. 3- and'9) isattaohed securely to the hub [9 of themain drive shaft 18 toenable the turning and stopping of the main drive gear 23 to be controlled from the main drive shaft (8 through action on ratchet wheel 22, rigidly attached to drive gear 23.

' The forward end of the hub portion 19 has a flat part 20 thereon as seen in Fig. 3, enabling the dial I to be locked o keyed to the main shaft by being provided with a central opening of corresponding non-circular shape.

The driving of the ratchet wheel 22, to thereby rotate the main drive gear 23, on the return or counter-clockwise movement of the dial l, is accomplished by drive pawl 3| (Fig. 3) pivoted to the drive plate 2| at 32, and urged inwardly toward ratchet wheel 22 by coil spring 34. Pawl 42, secured to portion 49 of bracket 46 at pivot 43, is provided to prevent forward or clockwise movement of the drive assembly when the dial 1 is being turned in a forward or clockwise direction toward the finger stop 4. For this purpose. the pawl 42 is provided with a coil Spring 45 (Fig. 3) urging the free end of the pawl into association with the teeth of ratchet wheel 22.

Brake pawl 35, pivoted at 36 on the drive plate 2 l, is provided to enable the return motion of the dial I and attached parts, together with the main drive gear 23 and attached ratchet wheel 22, to be stopped definitely when the returning dial reaches its illustrated normal position. The brake pawl has an'inner or heel po tion which contacts the rear face of one of the teeth of ratchet wheel 22 to stop the movement of the latter. This engagement is brought about during the return movement of the mechanism when the outer or cam portion of pawl 35 engages the inwardly inclined cam portion 38 of the comound bracket 46, securedto back plate I B by screws 41 and 48. The return movement is abruptly terminated when the outer portion of brake pawl 35 contacts the steeply inclined stop portion of bracket 46. p

The main drive gear 23, when rotated, turns the impulse pinion 25. attached to impulse shaft 24 (Figs. 4, 5. '7, and 8). Shaft 24 carries the impulse cam 26 and the governor-drive gear 21. being pivoted at one end in the back plate In and at the other end in the impulse-shaft bracket 29 (Figs. 3 and 8) The im ulse cam 26 normally stands in a position as illustrated in Figs. 2' to 5. with respect to the impulse contact spring 52 controlled thereby. The free end of the pair of contact springs 52 (seen in edge view in Fig. 8) is normally opposite one of the two cut-away portions of the cam 26. The impulse contacts 52 can thus be momentarily separated by either lobe of the cam 26 by half a rotation of the impulsecam shaft. i Y i v The shunt springs 53, seen in edge view in Fig. 8, are mounted in the same stackup or assembly with the impulse springs 52. Th impulse springs and shunt springs may be connected in multiple with each other by suitable wiring or strapping between the terminals 54. The purpose of shunt springs 53 is to enable the last impulse of a train generated at Springs 52 to be rendered ineffec-' tive by shunting the springs 52 under the control of shunt cam, 61, affixed to the drive plate 2|. Shunt springs 53 are normally maintained incontact with each other by pressure of cam portion Bl (Figs. 3 and 8) on. insulating stud 55 (Figs. 4 and 8) afiixed to the outer of the two springs 53.

As shown in Figs. 3, 4, and 6, a stackup 56 of oil-normal springs is provided. A stud 58 (Fig. 6) is affixed to one of the ofi-normal springs,

and an insulating portion 59 is fastened to the stud 58. This insulating portion 59 is controlled by off-normal cam 60, affixed to the drive plate 2|, to enable the off-normal contact springs 56 to shift their position when the dial is moved from its normal position.

As shown best in Fig. 9 (see also Figs. 6 to 8, and 13), the main spring 64 furnishes the motive power for returning the dial and related mechanism to normal position pursuant to the generation of a desired train of impulses during the return movement. This main spring 54 surrounds the portion of drive shaft [8 to the rear of the main-bearing bracket M, as well as surrounding a portion of the main bearing ll. At the opposite end, the spring 64 surrounds the inwardly extending thimble or guide portion H16 of adjustment washer 69. At its forward end, the spring 64 is attached to the main-bearing bracket 14 at 65 (Figs. 5 and 9) while the other end of spring 64 is attached to the adjustment washer 69 at 66 (Figs. 1 and 9).

Adjustment washer 69 is retained against rotation relative to shaft 18 by adjustment arm 61, whose forwardly turned end portion normally rests in one of the notches HI (Fig. 1) provided around the periphery of washer 69. Arm 6! is held firmly in place on the rear end of shaft l8 by screw 68. The spring 64 is preferably under slight longitudinal compression, whereby it tends to urge shaft l8 rearwardly and to hold adjustment washer 59 against bracket 6'1. 3

When the rotational tension of spring 64 is to be adjusted, the washer 69 may be pushed forwardly along the shaft 18 to bring the notches 10 free of the forwardly turned end portion of arm 67, whereupon the washer 69 may be rotated in either direction the desired amount to impart the desired restoring tension to spring 64. The new position of Washer 69 is retained by locking the concerned notch 10 over the end of arm 61.

It is to be noted that the central opening 63 through the back plate H1 is large enough to permit the spring 64 to pass through this opening and be attached to the bracket M as described. By this arrangement the spring is enabled to be longer than it would be if required to be attached to the rear face of the back plate It], whereby less variation in spring tension occurs between the beginning and end ofthe return movement of the dial.

The 7 speed of the return movement of the mechanism is limited by a governor shown at 94 (in Fig. '7 for example) protected by the pressed sheet-metal cover 93. This governor is of the magnetic-Weight type, being an improvement on the governor shown in the pending application of George R. Eaton, Serial No. 374,432, filed J anuary 15, 1941.

The governor includes a shaft indicated generally at H in the enlarged cross-sectional view (Fig. 10). Portion 12 of this shaft is journaled in the bearing member 62, secured in an opening through the back plate l0, while portion 13 is journaled inextension 30 (Figs. 3 to 5) of main bracket l 4. Governor shaft H is driven by pinion 28 from governor drive wheel 2'1, affiXed to impulse-cam shaft 24. v

The rotating system of the governor includes a pair of magnet weights 8|} and 8i (Figs. 1 and 12). These weights cooperate with the friction ring 94, aflixed to the back plate I!) as indicated in Fig. 10. Friction ring 94 is preferably of soft iron or other similar highly permeable, magnetically soft material.

' ing the velocity;

zposgseo The'srotatingassembly. of. thesgovernor includes thehub-portion. 'IIG: ('fig.v which has a central opening receiving the reduced-diameter portion I4 of: the shaft "I I. Hub-L portion 16. is. provided with a: pair: of cut-away or'flat'. portions. 'I-i'If (Fig. 12 with. which the downwardly turned ends of torque arm 18c make .contactto. prevent relative rotation of? parts Itand 18.. Relativerotation of part 1.8: and the threadedlshait-portion 'lfisis pro:-

vented-by the non-circular contour. ofithe. shait portion I5 as. shown. in Fig; 12; coupled .with. the corresponding contour of the. opening through part. I8. The governor shaft is: thus effectively keyed, through part I8, to the hub 16;.

The-weight. arm I9. is rigidly secured to=hub TE and is provided with pivot: pinsBQ-i and. as. for the two weights.

The above mentioned parts of therotatingsysitern are held in assembled. relation by nut i'fli, the'assembly being drawn-tight against the shoulder at the junction of shaft. portions 12 and; T4. The springeadjustment arm 81' (Figs: land-.10) i'sadjustabl'y held in from turning around. the shaft-portion by the retaining nut 33?.

The magnetic'w-eight portions fifltand Bil? (Figs. 1 and 12) are preferably cast: of a; magnetically hard-alloy of high coercivity, in order that. small Weights shall: have. a relatively great magnetic attraction. This magnetically hard. material, however (such as the well known aluminum;- nickel-cobalt alloy with steel), is very nearly completely: unmachineablea because of its extreme mechanical. hardnessz. This. materiah thereiore, must be cast in simple shapes andaattached by some means other than by drilled. holes. For this reason, the saddle arrangement indicated clearly in Fig: llzlSl provided". In this: arrangement, the saddle portion 33. may be formed; of sheet metal, for example; andv the block. bearing portion 92 (of common rolled stock) may be-sold'ered; brazed orotherwise-securedtc the portion 83. Bearing: portion 9.2;has. the illustratedbearing' hole therethrough for bearing pin; 98).. The construction of the opposite weightsadcheissimilar. The precast magnetic weights 8! and. 80 are laid intothe. saddle portions 82" and 83.: and secured in place: as by soldering:v The. portions 84 and 8.5 are attachment: points: for governor springs I031and': IDA, shown best in Fig; L. The

other ends of these springs: are attached to: the

ends of the adjustment arm: 81'.

The tension of both governor springs I03? and I04 can be conveniently adjusted at the same time by slightly loosening. the adjustment nut: 88 and turning the adjustment arm 81; to a desired new location, in which new location the arm. is heldby'r-etightening nut 88...

In the operation of the. governor; the springs I03- and HM hold the retarding weights. 8i]. and 81 out of'contact' with-the magnetic ring'tQk-uhtil the speed of the movement reaches the value forwhich the springs I03 and I104 are adjusted. At this point the centrifugal action causes the weights Ell-and 81 to: come sufiiciently near'the magnetic ring 94 that the magnetic attraction of the-weights 80 and' fit draws. them into firm engagement" with. the. ring; thus efiectivel'ybraki- The peak-velocity is" thus. critical and largely independent of the amount. of force being appliedto urge'the mechanism: to greater-speed, because the grabbing efiect oft-he magnetized weights introduces a large braking efiect at the critical velocity.

The opening I05 (Figs. 1 and 5) through. the

bach-pl'atel II- enables Wires connected to terminals- 54 of spring combinations: 52; and. lifiramti to terminals: 51. of:v the-ofi-normal springs 56., toihe broughtzthrougl r thev opening; I 0.5; and. connected (as. by soldering): to the terminals extending:.in:- WEIZCDHY' from the arcuatetterminal block; I.IID,-. see bestinJi'ig: 1.

Referring: to Fig.1:3, the: device 95imaybeia telephonedesk stand provided; with the;- usual opening therein for receiving the rear portion-.of the. calling device. This" opening ends: in an inwardly turned ledgeasindicated, which; stops the; inwardmovement of the cailing'device.v The mountingstrips 9.6 and 9.! lie in groovesin' this ledge: and. are held to-therear plate of the: calling deviceby retainingscrews 98. and. 9.9:.

As apparent from. the; foregoing: description in connection with. the drawings; the; principal moving parts of the calling device: and the. parts likely'to be disturbedin their state ofiadjustment by inadvertent contact; made during: transports. tion,.handling, and: installation. of the callingidavice, or during'repair of the; equipment withwhich itzmay be installed, are:enclosed:.within the-:hous; ing cup: 9 by' the; back plate Ill. The; two portions of. the calling device. sometimes requiring routine adjustment; such as: to compensate for wearor for" climatic variations, are. exposed: on the-rear of the devicev behind the back- Illa/1761' it. These. arerthe. main driving. springs 64: and. the governor includedi within? ring 9.4;. The main driving sprin may be? adjusted as: previously pointed out by depressing and turning the notched. adjusting washer 69.. This; spring is sufiiciently rugged? in. its construction; that; no special; protection thereof is. deemed to benecesisary; The governor, howeven. is provided: with the. cover 9-3 shown. in. place in: Figs. 7:, l0, and I3, protecting; the. governor against inadvertent interference. This. cover 9.3 may be removed when desired, to permit the hereinbefore, describert adjustment. of. the; governor to. be: made.

Operation The operation of the calling deviceto transmit a: train of: impulses. will now. be described. For this. purpose, it; may be assumed that atrain-..of impulses. corresponding; to the digit 8, and con:- sisting of eight: momentary interruptions, is to be transmitted. For this purpose,. the operator may place afinger in the finger hole of the; dial I above the digit 8' on. the numeral ring 3,. fol.- lowed. by a. rotation of the dial in. a clockwise direction. until the-finger strikes the finger stop 4-. The finger is. then removed. from the dial, allowing. the. dial to return to normal position under the; propulsion of the main spring 64;

As the: dial I is brought forward, in a clock- Wise: direction, the main. shaft I8 is thereby turned against the. tension of the main spring 64. The turning, of. the. hub portion I9 of the main shaft turns the drive-plate 2i. Thetur-ning at: this time of driving wheel 23 and ratchet wheel 2:2v isprevented. by pawl. 4-2. (Fig. 4)..

The; drivepawl; 3IT, secured to drive plate: 2d at pivot 32, rides over nine teeth of. ratchet. wheel 22. during; theiorwardmovement ofthe dial; one tooth. morev than the digit. value of the dial operation.v Each-time pawl 3-.I- passes over a. tooth, spring: 34- brings thev pawl sharply toward. the ratchet. wheel: 22:, but metallic clicking in this operationis prevented by the. non-metallic stop pin 33. which engages the periphery of. the. drive plate soon enough to prevent the point of: ratchet 3.1; from: clicking or: snapping; against the ratchet wheel;

movement of the calling device.

During the forward movement of the dial, drive plate 21 also carries the brakepawl 35 in a counter-clockwise direction. The pressure normally imparted to pawl 35 by cam surfaces 38 and 5| to hold the pawl tightly against the inclined face of one of the teeth of -ratchet wheel 22 is thereby relieved, and the pawl moves outwardly sufficiently to clear the teeth of the ratchet wheel.

Upon the initiation of the forward movement, and before the drive pawl 3| has passed over the first tooth on ratchet wheel 22, the off-normal cam-portion 60 (Figs. 3 and 6) of drive plate 2! disengages the insulating stud 59, permitting the olf-normal springs 56 to shift, to thereby set upthe usual altered circuit conditions conducive to efiective impulse transmission.

Also upon initiation of the forward movemen the elongated cam portion SI of drive plate 2| (Figs.'3, 6, and 8) begins to move over the surface of insulating bushing 55 attached to the uppermost spring of the shunt pair 53. The contact between cam portion BI and stud 55, however, is prolonged until after the ratchet 31 has passed over the first tooth of the ratchet wheel '22. This contact, however, is broken before the pawl 3| passes over the second tooth, whereupon the springs 53 (seen in edge view in Fig. 8) separate, thereby taking the shunt off the impulse springs 52, the springs '52 and 53 being intended to be connected in multiple as previously brought out.

When the dial l is released (after pawl 3|, Fig. 3, has passed over nine teeth of ratchet wheel 22), the inner portion of pawl 3| engages the rear face of the ninth tooth passed over. Therefore, during the return movement of the dial 1 and attached main shaft under the propulsion of main spring 64, the ratchet wheel 22 and attached main drive gear 23 are rotated in a counter-clockwise direction through an angular distance corresponding to nine teeth on ratchet wheel 22. The velocity of the return movement is controlled by the governor, illustrated in crosssection in Fig. 10, whose drive pinion 28 is rotated by governor drive gear 21 on impulse-cam shaft 24. The impulse-cam shaft in turn is driven by the attached pinion 25, through the motion of the main drive gear 23.

The impulse-cam shaft 24 makes a half revolution for each movement of the gear wheel 23 equal to the space of one tooth on ratchet wheel 22. Since the main drive gear is rotated an angular distance equal to nine teeth on the ratchet wheel 22, on the return movement, four and onehalf revolutions of the impulse-cam shaft 24 occur. A lobe of cam disc 23 passes between the impulse springs 53 and momentarily separates them during each half revolution of the impulse 'cam shaft. The impulse springs 52 are thus momentarily separated nine times on the return Ordinarily, speed of the return movement is so regulated that the impulses are generated at the rate of about ten per second.

The first eight separations of the impulse contacts 52 are eifective, but the ninth and final separation of the springs 52 is rendered-ineffective by shunt springs 53, which are reclosed following the eighth separation, when the cam portion 6! again contacts insulating stud 55 (Figs. 4 and 8) to again bring shunt springs 53 into contact.

During the return movement, when the ratchet wheel 22 and related parts are being driven in a counter-clockwise direction, teeth of the ratchet wheel 22 successively pass under pawl 42 (Figs. 3 and 4), causing this pawl to be successively raised against the tension of spring 45 and lowis made. 5 v

ered into the next succeeding notch in the ratchet wheel. Mechanical clicking is prevented durin this operation by the non-metallic stop 44 which prevents the free end of pawl 42 from striking the next succeeding tooth when dropping over the rear face of the tooth passing under it.

As the dial (together with its attached parts, including drive plate 2|) approaches normal position, the outer part of brake pawl 35 (Fig. 3) engages the cam portion 38 of bracket 46 and is turned in a clockwise direction about pivot 36 against the tension of spring 39 to bring the free end of the pawl radially inward. As the return motion continues, the brake pawl is brought closer and closer to the rear face of the currently underlying tooth of ratchet wheel 22 (the ratchet wheel and the drive plate are traveling together at this time) until the tooth is engaged or nearly engaged. When the normal position is reached, the outer portion of brake pawl 35 is forced abruptly inwardly by cam portion 5| to jam it against the last-mentioned tooth of ratchet wheel 22, thereby stopping the forward motion of ratchet wheel 22 and of drive plate 2i. The motion of all parts of the calling device is thereby arrested.

I claim:

1. In a dial-controlled impulse sender, an enclosing case containing dial-controlled mechanism for controlling the generation of series of impulses, a central shaft within said case eXtending through an opening in the front of the case and through an opening in the rear thereof, said shaft being iournaled in a bearing within said case, said shaft having a normal position from which it; is rotatable by said dial when the dial is turned, said mechanism being controlled by said shaft during its return to normal position for causing a train of impulses to be generated, a main spring for returning said shaft to normal position, said main spring surrounding the rear portion of said shaft from a point outside of said case to a point lying within said case, the inner end of said spring extending through said opening in the rear of the case and being attached to a part affixed to the case, while the outer end of said. spring is adjustably attached to said shaft.

2. In a dial-controlled calling device, a dial rotatable a variable angular distance in one direction from a normal position to prepare for the generation of a train of impulses on its return movement, means including a pivoted pawl and a ratchet wheel to permit the forward movement of the dial to occur without a corresponding movement of the impulse generating mechanism, and means for preventing-mechanical clicking of the pawl on said ratchet wheel during the forward movement of the dial, said means including a rigid non-metallic stop device so located as to stop-the pivoting movement of the pawl toward the ratchet wheel before it has engaged the ratchet wheel after having slipped over a tooth thereof, said stop device being located a distance from the pivot of the pawl which is substantially less than the length of the pawl, whereby the tendency of the pawl to produce a clicking noise when stopped is lessened by the reduced velocity of the part with which the stopping engagement JAMES E. Bos Y 

